With my Dragon 700 the only way I could use the top 3/8" of the primary and break 100 mph was with HC drag and flys. I had the same issue, I used weights with more tip mass and couldnt rev out. I used less and wasnt shifting out. For that sled, drag and flys were the shit. I picked up 12 mph once it was properly clutched---honestly. It sounds to me like your not making 140 hp for whatever reason. You could be hitting 8500 but have a powervalve, low compression, chipped reeds, worn reeds, rich jetting, weak ignition or something going on other than your clutching. My 02 is stock and original with 4k miles and only has a roller secondary with a crazy steep 64/44 helix with a cat red/white spring and in 40 degree weather I was pulling big top end numbers. My primary is all stock too. I did find earlier this yr that my mag cylinder powervalve was waaaaay out of adjustment and not opening all the way...